Set of equipment comprising an inflatable structure and a frangible fixing member, and corresponding vehicle

ABSTRACT

This set of equipment for a motor vehicle includes an inflatable structure, an element acting as a support for the inflatable structure, an element forming a load-spreading plate and at least one frangible member for fixing the load-spreading plate to the support. The set includes a sheath, an open first end which is fixed to the support and an open second end which is fixed to the load-spreading plate to form the inflatable structure. The frangible member includes a thin web, a peripheral region which is fixed to a first element, either the load-spreading plate or the support, and a central region which is fixed to the other of these elements.

BACKGROUND OF THE INVENTION

The present invention relates to a set of equipment for a motor vehicle,of the type comprising:

-   -   an inflatable structure,    -   an element forming a support for the inflatable structure,    -   an element forming a load-spreading plate spreading the load of        an impact of an occupant of the motor vehicle with the deployed        inflatable structure, and    -   at least one frangible member for fixing the load-spreading        plate to the support, the frangible member being intended to        break as the inflatable structure deploys.

The invention applies in particular to sets of equipment comprisinginflatable structures for protecting the knees of the occupants of motorvehicles.

DESCRIPTION OF THE RELATED ART

A set of the aforementioned type is known in such an application fromdocument U.S. Pat. No. 6,131,950.

In that document, the inflatable structure comprises an open first endfixed to the support and a second end formed of an integrally formed endwall. The end wall of the structure is fixed to the load-spreadingplate. This fixing is provided along the edge of the load-spreadingplate by virtue of a strengthening ring stitched into the structure andhoused in a rim of the load-spreading plate.

This set of equipment proves to be costly to produce because it entailsa great many components and a large amount of material.

SUMMARY OF THE INVENTION

One object of the invention is to solve this problem by providing a setof equipment of the aforementioned type which costs less to produce.

To this end, the subject of the invention is a set of equipment of theaforementioned type, characterized in that the set comprises a sheath,an open first end of which is fixed to the support and an open secondend of which is fixed to the load-spreading plate, the inflatablestructure being formed by the sheath and the load-spreading plate whichcloses off the second end of the sheath, and in that the frangiblemember comprises a web, a peripheral region of which is fixed to a firstelement, either the load-spreading plate or the support, and a centralregion of which is fixed to the other of either the load-spreading plateor the support.

According to some particular embodiments, the set of equipment may haveone or more of the following feature(s) taken in isolation or in anytechnically feasible combination:

-   -   an intermediate region of the thin web, situated between the        central region and the peripheral region, is a region of lower        strength,    -   the peripheral region of the thin web is fixed to the first        element by clamping means,    -   the central region of the thin web is fixed to the second        element by clamping means,    -   the clamping means comprise at least one end-piece with an        enlarged head,    -   the first end of the sheath is fixed by being trapped between        the first element and the peripheral region of the thin web,    -   the second end of the sheath is fixed by being trapped between        the second element and the central region of the thin web,    -   the first element is the support and the second element is the        load-spreading plate,    -   the set constitutes a set for protecting the knees of an        occupant of a motor vehicle.

Another subject of the invention is a motor vehicle characterized inthat it comprises a set of equipment as defined hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from reading the descriptionwhich will follow, given solely by way of example made with reference toFIGS. 1 to 3:

FIG. 1 being a schematic longitudinal section of a set of equipmentaccording to a first embodiment of the invention,

FIG. 2 being a schematic perspective view of the thin web for fixing theload-spreading plate to the support of the set of FIG. 1, and

FIGS. 3 and 4 being views similar to FIG. 1, on a smaller scale,illustrating the deployment of the inflatable structure of the set ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In all of that which follows, the orientations used are the customaryorientations of a motor vehicle. Thus, the terms “front”, “rear”, “top”and “bottom” are to be understood with respect to the position of adriver of the motor vehicle and its direction of travel.

FIG. 1 schematically illustrates a set of equipment 1 for a motorvehicle, in the form of a door to a storage binnacle for housing items.This storage binnacle is provided in the instrument panel. The door 1therefore forms part of the instrument panel. It is arranged more orless facing the knees of a passenger of the motor vehicle.

The door 1 is conventionally hinged to the remainder of the instrumentpanel to allow access to the storage binnacle.

The elements of the instrument panel other than the door 1 areconventional. They have therefore not been depicted in the figures andwill not be described in detail hereinafter.

The door 1 essentially comprises:

-   -   an inflatable structure 2,    -   a front support 4 for the inflatable structure 2,    -   means 6 for inflating the structure 2,    -   a load-spreading back plate 8 for spreading the load when a        passenger impacts with the structure 2, and    -   a frangible thin web 10 for fixing the load-spreading plate 8 to        the support 4.

The inflatable structure 2, comprises, on the one hand, a sheath 12which forms its lateral wall, and comprises, on the other hand, thecentral zone 14 of the load-spreading plate 8 which forms its end wall,as will be described hereinafter.

The sheath 12 is made, for example, of a braided or woven material andhas an open front first end 16 and an open rear second end 18.

The structure 2 has a furled configuration depicted in FIG. 1 and adeployed configuration depicted in FIG. 4.

In the deployed configuration, the sheath 12 converges from its frontend 16 towards its rear end 18.

The sheath 12 is then stretched between its ends 16 and 18 and extendsalong a directrix mid-line L that is roughly horizontal in FIG. 4. Thesheath 12 near its front end 16 and about the line L has a more or lessrectangular outline.

Near the rear end 18 and about the line L the sheath 12 has a similaroutline, but of a smaller size.

The upper region 20 of the sheath 12 is appreciably shorter, in theplane of FIG. 4, than the lower region 22 of the sheath 12.

It will be understood that the abovementioned geometric features arespecific to the embodiment of FIGS. 1 to 4 and may, in alternativeforms, be absent.

The support 4 forms an interior lining for the door 1. The support 4comprises a peripheral surround 24 internally delimiting an opening 26,and a cover 28 closing the opening 26.

The peripheral surround 24 and the cover 28 are made, for example, ofplastics material(s).

The cover 28 is fixed to the surround 24 by the clip-fastening offingers 30 which extend the cover 28 rearwards and are housed inopenings 32 formed in the surround 24.

The cover 28 is arranged in front of the surround 24 and theclip-fastening has been achieved by moving the cover 28 backwards anddownwards with respect to the surround 24.

The means 6 for inflating the structure 2 comprise, for example, a gasgenerator 6 attached to the cover 28.

The generator 6 is of conventional type and its structure will thereforenot be described in greater detail hereinafter.

The generator 6 is fixed to the rear face of the cover 28 and thereforefaces the load-spreading plate 8.

The load-spreading plate 8 forms, when the structure 2 is in the furledconfiguration and the door 1 is closed as depicted in FIG. 1, a part ofthe exterior surface of the instrument panel and may therefore, forexample, like it comprise a layer of plastics material covered with acovering skin.

As illustrated more specifically in FIG. 2, the thin fixing web 10comprises a rear central region 34 with a roughly rectangular outline,an intermediate region 36 which extends the rear central region 34forwards and a front peripheral region 38 which extends the intermediateregion 38 outwards and, for example, comprises four tabs 40, each onearranged on one side of the intermediate region 36.

The intermediate region 36 is a region of lower strength.

In one embodiment, this region of lower strength is obtained by virtueof recesses 42 made in the region 36 and between them delimitingfrangible small bridges 44 connecting the central region 34 to theperipheral region 38.

This region of lower strength works in pure tension. This embodiment“with frangible small bridges” offers an advantage over the “V-shaped”weakened lines customarily used in airbag covers because as the crosssections of the frangible small bridges 44 can easily be sized, therupture load is very repeatable, and less dependent on temperature andon structure inflation conditions.

The thin fixing web 10 has, for example, been produced by moulding aplastic material.

The peripheral region 38 of the thin web 10 is fixed to the surround 24of the support 4. This fixing is provided in the example depicted byend-pieces 46 which extend the peripheral region 38 forwards and arehoused in orifices 48 of the surround 24. The front ends 50 of theend-pieces 46 have been deformed, for example by melting, to formenlarged heads providing a rigid connection between the peripheralregion 38 of the thin web 10 and the surround 24 of the support 4. Theend-pieces 46 and their heads 50 therefore form rivets clamping the thinweb 10 on the support 4.

The front end 16 of the sheath 12 is trapped between the surround 24 andthe peripheral region 38 of the thin web 10, thus fixing this front end16 to the support 4.

It will be noted that the end-pieces 46 therefore pass through orificesmade in the front end 16 of the sheath 12 in line with the orifices 48.

Likewise, the central region 34 of the thin web 10 is fixed to thecentral zone 14 of the load-spreading plate 8 by end-pieces 52 whichextend the zone 14 forwards and are housed in orifices 54 of the centralregion 34 of the thin web 10. The front ends 56 of the end-pieces 52have been deformed by melting to form enlarged heads. The end-pieces 52therefore constitute rivets clamping the thin web 10 to the plate 8.

The rear end 18 of the sheath 12 is trapped between the central region34 of the thin web 10 and the central zone 14 of the plate 8. Thus, theend 18 is fixed to the load-spreading plate 8. Furthermore, the zone 14of the load-spreading plate 8 covers over the rear end 18 of the sheath12 and therefore forms the end wall of the structure 2.

To produce the door 1, the sheath 12 is slipped over the thin web 10,and then the central region 34 of the thin web 10 is fixed to theload-spreading plate 8, at the same time fixing the rear end 18 of thesheath 12 to the plate 8. It will be noted that the sheath 12 slippedonto the thin web 10 is then prepositioned. In an alternative form thathas not been depicted, the thin web 10 may comprise, in addition to theend-pieces 46, positioning studs intended to be engaged in openings inthe sheath 12.

Next, the surround 24 is fixed to the peripheral region 38 of the thinweb 10, making it possible simultaneously to fix the front end 16 of thesheath 12 to the surround 24.

Finally, the cover 28, already equipped with the gas generator 6, isfixed on, by clip-fastening onto the surround 24.

If an accelerometer, not depicted, connected to the gas generator 6detects an impact, this triggers the operation of the generator 6. Thegas produced by the generator 6 fills the interior volume of thestructure 2 initially in the furled configuration, until the pressureexerted on the central region 34 of the thin web 10 is high enough tobreak the small bridges 44 of the thin web 10.

Once these small bridges 44 have been broken, the central region 34 ofthe thin web 10 is separated from its peripheral region 38 and theload-spreading plate 8 can move with respect to the support 4.

The structure 2 then begins to deploy as illustrated in FIG. 3.

This initial deployment is in a direction of inflation D more or lessorthogonal to the cover 28 of the support 4, and therefore inclineddownwards and backwards. During this initial phase of the deployment ofthe structure 2, the load-spreading plate 8 therefore has a tendency tomove backwards and downwards, as illustrated by the arrow 58 in FIG. 3.

The diagonal d1 (in dotted line) connecting the upper edge of the frontend 16 of the sheath 12 to the lower edge of the rear end 18 of thesheath 12 will become taut before the diagonal d2 (in dotted line)connecting the lower edge of the front end 16 to the upper edge of therear end.

The side regions of the sheath 12, which connect the upper 20 and lower22 regions, and which will become taut along the diagonal d1 willtherefore cause the load-spreading plate 8 to pivot upwards until theside regions are taut along the diagonal d2.

Thus, in the terminal phase of deployment of the structure 2, theload-spreading plate 8 no longer moves in the direction of inflation Dbut diverges gradually from this direction to become centred, in thedeployed configuration of FIG. 4, on the line L.

The load-spreading plate 8 is therefore at the end deployment of thestructure situated above the direction of inflation D, properly facingthe passenger's knees. The sheath 12 is then taut from its front end 16to its rear end 18 which means that the directrix line L runs more orless horizontally at an angle θ to the direction of inflation D.

Next, when the passenger's knees strike the load-spreading plate 8, thisplate spreads the load applied by the knees over practically its entirearea and thus allows the structure 2 to satisfactorily deaden the impactof the passenger's knees with the instrument panel.

The set of equipment 1 described hereinabove has the followingadvantages.

By virtue of the use of the frangible thin web 10, the load-spreadingplate 8 is attached to the support 4 without any take-up of play beingneeded.

Furthermore, this attachment is reliable which means that any play andoutward projection that appear over time are limited. Thus, thevibrations likely to arise over time as the vehicle runs along arelimited.

The aesthetic appearance of the set 1 is therefore satisfactory, andthis is achieved at low cost.

Furthermore, the thin fixing web 10 is used both for prepositioning andfor fixing the sheath 12 and therefore makes it possible to achieve lowproduction costs.

Furthermore, the number of components used is low, making it possible toreduce production costs accordingly. It will also be noted that themoulding of the thin web 10 requires few moving parts in the mould andthat the thin web 10 can easily be released from the mould. Its cost ofmanufacture is therefore low.

Even so, the thin web 10 makes it possible to achieve breakage under arelatively low and well-defined load.

In addition, the thin web 10 forms a member that strengthens theload-spreading plate 8, making it possible to reduce its thickness andtherefore the cost of the set 1.

In other alternative forms that have not been depicted, the fixing ofthe central region 34 and of the peripheral region 38 of the thin web 10to the load-spreading plate 8 and to the support 4 may be performedusing means other than those described.

In particular, use may be made of welding and/or clip fasteningtechniques.

In another embodiment that has not been depicted, the thin web 10 may beconnected by its central region to the support 4 and by its peripheralregion to the load-spreading plate 8.

Furthermore, the sheath 12, which is taut in the deployed configurationof the structure 2, itself forms the means of guiding the structure asits deploys, making it possible further to reduce the cost of the set 1.

It will be noted that this feature can be used independently of the useof the frangible thin web 10 and of the embodiment of the structure 2 inthe form of a sheath with two open ends.

Thus, the structure 2 may be a conventional structure with an end wallformed integrally with its lateral wall, which forms the means ofguiding the structure as it deploys.

More generally, it will be noted that these principles may be used toguide the structure 2 along a directrix line L which may be offsetlaterally and/or vertically with respect to the direction of inflation Dso as to achieve the desired end position for the load-spreading plate8.

In general also, the sheath 12 may, in addition to guiding the structureas already described, alter the orientation of the load-spreading plate8 with respect to the support 4.

Specifically, in the example described hereinabove, the plate 8 remainsmore or less parallel to the support 4. However, by altering the lengthsof the upper 20, lower 22 and side regions of the lateral wall of thestructure it is possible to modify the orientation of the plate 8 withrespect to the support 4.

In a way that is more general yet, auxiliary guide means may beassociated with the guide means formed by the lateral wall of thestructure which becomes taut more or less between the front end 16 andthe end wall 14 of the structure. These auxiliary guide means maycomprise a rim of the instrument panel which will retain the lower edgeor upper edge of the load-spreading plate 8 at the start of inflation ofthe structure.

1. Set of equipment for a motor vehicle, comprising: an inflatablestructure, an element forming a support for the inflatable structure, anelement forming a load-spreading plate spreading the load of an impactof an occupant of the motor vehicle with the deployed inflatablestructure, and at least one frangible member for fixing theload-spreading plate to the support, the frangible member being intendedto break as the inflatable structure deploys, wherein the set comprisesa sheath, an open first end of which is fixed to the support and an opensecond end of which is fixed to the load-spreading plate, the inflatablestructure being formed by the sheath and the load-spreading plate whichcloses off the second end of the sheath, and wherein the frangiblemember comprises a web, a peripheral region of which is fixed to a firstelement, either the load-spreading plate or the support, and a centralregion of which is fixed to the other of either the load-spreading plateor the support, the web being placed inside a space delimited by thesheath, the support and the load-spreading plate.
 2. Set of equipmentaccording to claim 1, wherein an intermediate region of the web,situated between the central region and the peripheral region, is aregion of lower strength.
 3. Set of equipment according to claim 1,wherein the peripheral region of the web is fixed to the first elementby clamping means.
 4. Set of equipment according to claim 3, wherein theclamping means comprise at least one end-piece with an enlarged head. 5.Set of equipment according to claim 1, wherein the central region of theweb is fixed to the second element by clamping means.
 6. Set ofequipment according to claim 1, wherein the first end of the sheath isfixed by being trapped between the first element and the peripheralregion of the web.
 7. Set of equipment according to claim 1, wherein thesecond end of the sheath is fixed by being trapped between the secondelement and the central region of the web.
 8. Set of equipment accordingto claim 1, wherein the first element is the support and the secondelement is the load-spreading plate.
 9. Set of equipment according toclaim 1, the set constituting a set for protecting the knees of anoccupant of a motor vehicle.
 10. Motor vehicle, comprising a set ofequipment according to claim 1.